NASA reported on Thursday that those 10 finds are the first of what scientists hope will be hundreds of black hole discoveries.

The 10 black holes detected are what NASA calls "gargantuan structures." The black holes are surrounded by thick disks of gas and lie at the hearts of distant galaxies between 0.3 billion and 11.4 billion light-years from Earth.

A black hole is an area in space with such intense gravitational pull that matter, and even light, cannot escape it.

"We found the black holes serendipitously," said David Alexander, a NuSTAR team member based in the Department of Physics at Durham University in England. "We were looking at known targets and spotted the black holes in the background of the images."

The spacecraft, which consists of a telescope with a mast the length of a school bus, was launched into Earth orbit in June 2012. It's the first telescope capable of focusing high-energy X-ray light into detailed pictures.

According to the space agency, by combining observations taken across the range of the X-ray spectrum, astronomers hope to crack unsolved mysteries of black holes, such as how many there are in the universe.

The space telescope will make targeted surveys of areas of space in the hunt for more black holes, NASA said. However, scientists also intend to scan hundreds of other images that the telescope has taken in the hopes of finding black holes in the background.

For instance, once NuSTAR spotted the first 10 black holes, scientists went back to study images taken by other telescopes, including NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite. Scientists found that images of the black holes had been caught by these other devices but weren't spotted without closer inspection.

"We are getting closer to solving a mystery that began in 1962," Alexander said in a statement. "Back then, astronomers had noted a diffuse X-ray glow in the background of our sky but were unsure of its origin. Now, we know that distant supermassive black holes are sources of this light, but we need NuSTAR to help further detect and understand the black hole populations."